The invention relates to a gas valve unit for setting a gas volume flow supplied to a gas burner of a gas appliance, in particular a gas cooker, the gas valve unit having a valve housing and an actuation pin, an operating segment of which projects from the valve housing and a shutoff valve being configured in the valve housing.
Gas valves of such design are frequently referred to as safe gas valves. The gas valve unit has a variable cross section, which can be set by way of the actuation pin. The opening cross section here can be set infinitely. The size of the gas volume flow flowing through the gas valve unit and therefore also the flame size at the gas burner are a direct function of the opening cross section. Generally with generic gas valve units the opening cross section can be set to zero, in other words the gas valve unit can be closed completely.
The gas valve unit also has a shutoff valve that can be actuated independently of the setting of the opening cross section. The shutoff valve generally has an open switching position and a closed switching position but no intermediate positions. When the shutoff valve is closed, the gas flow through the gas valve unit is stopped completely. In contrast the opened shutoff valve has no influence on the opening cross section of the gas valve unit. The shutoff valve serves on the one hand to ensure complete closure of the gas valve unit in a redundant manner. On the other hand it is possible to actuate the shutoff valve automatically for example as a function of the signal from a flame sensor.
Known gas valve units of the type mentioned in the introduction are generally embodied as plug valves. The opening cross section here is set as a function of the rotation position of a plug that can be rotated in a valve seat. The actuation pin is disposed coaxially to the plug and connected thereto. The opening cross section of the gas valve unit is set by rotating the actuation pin. The shutoff valve can be opened by pushing the same actuation pun.
Gas valve units of such design frequently have an unfavorable switching response. In particular the opening cross section can frequently only be set in an imprecise and non-reproducible manner.